Cartridge shell



Sept., 118, 1934. Lm A. GUIGNET @9974379 CARTRIDGE SHELL Filed Marchi,1.955

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Patented Sept. 18, 1934 y 1,974,270 CARTRIDGE SHELL Lon Auguste Guignet,La Varenne Ste. Hilaire,

Pjrance, assignor to Compagnie Royale Asturienne des Mines, Paris,France, a corporation of ,Belgium Application March 1, 1933, Serial No.659,115 In Germany January 1,7, 1933 Claims.

r.This invention relates to drawn metal cartridge shells having a doublecircumferential fold between the base and the tubular part of the shell.

y Metal shells in accordance with the present ine vention are especiallysuited for sporting cartridges because they are moisture proof and aretherefore preferable to the cardboard shells used. extensivelyheretofore. I-Ieretofore the crowns of such double folds were tightlyclosed so that 10.' adjacent layers of the fold touch each other oversubstantially their entire length. While such folds were intended tostrengthen the base, they were not permanently gas tight as the materialin the crowns of the fold was over-strained during '1'5- the manufactureto a point where incipient cracks developed therein which opened up whenthe cartridge was fired, or the material was weakened to a degree thatit could not withstand the firing pressure.

The present invention has for its object to provide a cartridge shellwhich avoids the aforementioned disadvantages.

Another object is to provide a cartridge shell which does not crack uponiiring and which therefore can be employed with safety.

Another object is to provide a cartridge shell of relatively lightweight in relation to the pressure which is developed therein uponfiring.

Another object is to provide a cartridge shell with a double foldbetween the rim of the base and the tubular part which fold forms anelastic spring-like connection between the parts capable of yieldingupon ring and thus reduces the strain upon the shell.

Another object is to provide a cartridge shell with a double fold inwhich the maximum stresses to which the material is subjected duringmanufacture and during subsequent firing are relatively low.

Another object is to provide a cartridge shell of a material which isreadily formed, which is inexpensive and which is especially suited forthe purpose.

The accompanying drawing illustrates one embodiment of my invention.

In the drawing,

Figures 1 and 2 are longitudinal cross sections of a cartridge shellduring different stages of the manufacturing process, while Fig. 3 is alongitudinal section of the lower part of the iinished shell.

Referring to the drawing, the shell which has a tubular part 1 and abase 2 is first cold drawnin the usual manner, the bottom having aconstant 55. thickness and the wall of the tubular part being slightlytapered as shown in Fig. 1. It will be understood that the proportionsshown in Figs. 1 and 2 are somewhat exaggerated. As an example thethickness of the top end of the tubular part in the stage shown in Fig.1 may be .23 mm., while 6o the thickness of the tubular part near thebase may be .35 mm. and the constant thickness of the base .7 mm.

By subjecting the shell blank to a further operation, it attains theform shown in Fig. 2 where-V 65 in the length of the tube is increasedand the bottom is approximately hernispherical. Thereafter the blank isput into another tool which gives it its nal shape as illustrated inFig. 3 and in which the double fold between the wall l and the rim 3 ofthe base 2 is designated by the numerals 4 and 5. It will be observedthat the thickness of the wall in the rst bend 4 near the rim 3 isslightly tapered and that the crowns 0i the fold are given radii whichare large in relation to the thickness of the metal and the sidesthereof are oblique to the base. The cross section of the entire doublefold represents a substantially continuous curve as distinguished from abend consisting of a combination of curves and straight lines. By virtueof this construction, over-straining and cracking of the outside fibersof the turns during manufacture or firing is avoided, and the doublefold when subjected to the lateral and radial gas pressure resultingfrom firing, yields suciently to reduce the maximum strain upon thematerial to a safe value.

I have also found that certain materials are especially suitable forcartridge shells of the type described herein. Pure zinc, which isreadily worked into the proper shape, is too soft for a cartridge andwill not withstand the firing pressures. Commercial brass is relativelyexpensive and cannot readily be drawn into my preferred form. After manyexperiments I have discovered that an alloy of copper and zinc having avery high zinc content is especially suitable for cartridge shells. Asan example, an alloy of 99.5% by weight of Zinc and .5% by weight ofcopper is readily shaped and readily withstands the firing pressure.

While I have specified in the appended claims an alloy of 99.5% byweight of zinc and .5% by weight of copper, I do not wish to limitmyself to the exact proportion but any alloy of zinc and coppercontaining between .4% and 1% of copper is deemed to come within thescope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:-

1. A metal cartridge shell having between its base and its tubular parttwo resilient folds which are reversed relative to each other, saidfolds including arcs of more than a' half-circle and having relativelylarge inside radii.

2. A metal cartridge shell provided with a resilient double fold betweenthe base and the tu- Y buiar part of the shell, the crowns of said foldhaving relatively large inside radii, said shell consisting of an alloyof zinc and copper containing approximately .5% by weightY of Copper.

3. A metal cartridge shell having between its base and its tubular parttwo resilient folds which are reversed relative to each other, saidfolds including arcs of more than a half-circle and having relativelylarge inside radii, the

Ying relatively large inside radii, the change in curvature between thefolds being substantially continuous, the thickness of the Wall alongsaid Walls being tapered.

LoN AUGUSTE GUIGNET.

